Move

EXERCISE: WHAT’S THE PROBLEM?

Everywhere we look, we are bombarded with messages to exercise more. We are also told about the rising rates of obesity and offered statistics such as these from the Health and Social Care Information Centre (HSCIC) for 2012-2013 (Source here):

Obesity admissions for women more than twice as high (8,010) as those for men (2,950)
Figures for 2012-13 are similar to those in 2011-12 where there were 8,740 admissions for women and 2,990 admissions for men, and compares to 850 women and 430 men in 2002-03.5
In 2012-13, obesity admissions were lower than in 2011-12 in each age group except for those aged under 16 (560 from 500 in 2011-12, a rise of 12 per cent), and those aged 65 and over (590 from 560 in 2011-12, a rise of 6 per cent).
Bariatric surgery procedures were over three times as common in women (6,080) than in men (1,940), and this has been the pattern for the last ten years
In 2012, approximately a quarter of the adult population was obese (24 per cent of men and 25 per cent of women).

There is no doubt that there is a major problem, but can exercise help us?

RECOMMENDATIONS

Here is the recommended physical activity for adults aged 19-64 from the NHS website (Source here):

At least 2 hours and 30 minutes of moderate-intensity aerobic activity such as cycling or fast walking every week PLUS muscle-strengthening 2 or more days a week that work all major muscle groups

OR

1 hr 15 mins of vigorous-intensity aerobic activity such as running PLUS muscle-strengthening activities on 2 or more days a week

On first glance, that seems sensible enough to most people. However, can we learn anything from our cavemen ancestors regarding exercise to help us? The nearest equivalent we have to look at is modern hunter-gatherer tribes and although not a perfect comparison, they give us some idea of how Paleolithic humans may have moved in their day to day lives.

WHAT DID OUR ANCESTORS DO?

Contrary to what we may suppose, our ancestors may have moved only insomuch as doing what was required to survive on a day to day basis. Their ‘exercise’ may have involved:

Long periods of gentle activity such as walking

Short bursts of intense physical activity followed by rest

A variety of different movements

Being outdoors in a natural environment

Yes we have gone from a vigorous and physically demanding lifestyle to one that is largely sedentary in the blink of an eye and this has resulted in many physical problems. BUT as we shall see, researchers think that lack of exercise is NOT the cause of the obesity epidemic. Read on…

HUNTER-GATHERER GENETICS AND HUMAN OBESITY

The report measured total daily energy expenditure (TEE) in Hadza hunter-gatherers of Tanzania – to test whether foragers expend more energy each day than their Western counterparts.

The Hadza live in simple grass huts in the middle of a dry East African savannah

They have no guns, vehicles, crops or livestock.

Each day the women comb miles of hilly terrain, foraging for tubers, berries and other wild plant foods, often while carrying infants, firewood and water.

Men set out alone most days to collect honey or hunt for game using handmade bows and poison-tipped arrows, often covering 15 to 20 miles.

Obesity and heart disease are unheard of and 80-year-old grandmothers are ‘strong and vital.’

RESULTS

‘As expected, physical activity level, PAL, was greater among Hadza foragers than among Westerners. Nonetheless, average daily energy expenditure of traditional Hadza foragers was no different than that of Westerners after controlling for body size.’

‘The similarity in metabolic rates across a broad range of cultures challenges current models of obesity suggesting that Western lifestyles lead to decreased energy expenditure.’

‘TEE is remarkably similar across a broad, global sample of populations that span a range of economies, climates, and lifestyles’

‘We hypothesize that TEE may be a relatively stable, constrained physiological trait for the human species, more a product of our common genetic inheritance than our diverse lifestyles.’

‘Our results indicate that active, “traditional” lifestyles may not protect against obesity if diets change to promote increased caloric consumption.’

‘We think that the Hadzas’ bodies have adjusted to the higher activity levels required for hunting and gathering by spending less energy elsewhere.’

‘a growing body of evidence suggesting that energy expenditure is consistent across a broad range of lifestyles and cultures.’

‘We can increase energy expenditure in the short term, but are bodies are complex, dynamic machines, shaped over millions of years of evolution in environments where resources were usually limited; our bodies adapt to our daily routines and find ways to keep overall energy expenditure in check.’

Exercise will not solve the obesity crisis- the problem is food. Yes, we want to exercise for the myriad other benefits that it brings such as cardiovascular fitness (although see the quote from Mark Sisson below), muscular and skeletal strength, improved glucose and lipid metabolism, immunity, improved mood and sounder sleep. Those benefits are fantastic and are reasons to exercise in themselves. However when it comes to obesity rates, is health advice wrong to focus on lack of exercise as equivalent in importance to food? Read the work of Gary Taubes – in particular Good Calories Bad Calories for more discussion on this.

HOW SHOULD WE MOVE?

Let’s start with a warning that may go against much of the exercise advice given in the mainstream (including the NHS guidelines above):

NO CHRONIC CARDIO!

What on earth is that? Let’s get the advice of Mark Sisson, who coined the phrase:

‘Chronic cardio is ANY ACTIVITY THAT PUSHES THE HEART RATE OVER 75-80% FOR SUSTAINED PERIODS’.

Chronic cardio:

raises cortisol levels

increases oxidative damage

increases systemic inflammation

depresses the immune system

decreases fat metabolism

‘Although it improve cardiac muscle strength you get to the point of diminishing returns fairly quickly’ Mark Sissons